Methyl 3-bromobutyrate is an organic compound with the molecular formula C5H9BrO2. It is a colorless to pale yellow liquid with a characteristic ester odor. Structurally, it features a bromine atom at the beta position relative to the ester carbonyl group, making it a versatile β-bromo ester. This compound is primarily used as a valuable synthetic building block and reagent in organic chemistry. The bromine atom serves as a good leaving group, enabling various nucleophilic substitution reactions. It is particularly useful in the synthesis of γ-butyrolactones and other heterocyclic compounds. Additionally, it can act as a precursor for the preparation of 3-substituted butyric acid derivatives through further functional group transformations. As a halogenated ester, it requires careful handling. It is typically flammable and may cause skin and eye irritation. It should be stored in a cool, well-ventilated area away from incompatible materials such as strong bases and oxidizing agents.